Toilet tank



FIG. 1 is a perspective view of a toilet tank showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines in the figures are included for the purpose of illustrating portions of the toilet tank that form no part of the claimed design. 

CLAIM The ornamental design for a toilet tank, as shown and described. 